Summary of Work: During the past year, the Membrane Signaling has reported two novel mechanisms for potassium channel regulation by signal transduction pathways: the association of calcium-activated potassium channels with cAMP-dependent protein kinase through a leucine zipper domain; the regulation of potassium channels by death receptors in lymphocytes. In addition we have initiated a new molecular study into the regulation of cardiac calcium channels by dihydropyridines, which are used to treat human cardiovascular disease. These mechanisms provide new targets for investigating the disruptive effects of environmental toxicants on cell function.